Pre-expanded particles of non-crosslinked linear low density polyethylene

Abstract

A pre-expanded particle of a non-crosslinked linear low density polyethylene having an average cell diameter as large as 120 to 1,200 mu m which can be molded, without further imparting an expandability prior to molding or without aging under pressure, by heating in a closed mold permeable to a fluid heating medium such as steam to form a well bonded unitary cellular molded article having a good appearance, a high expansion ratio and improved heat resistance and mechanical property with a slight volumetric shrinkage.

What is claimed is: 
     
       1. A pre-expanded particle of a non-crosslinked linear low density polyethylene having an average cell diameter in the range of 320 to 1,200 μm and prepared from a copolymer of ethylene and a C 4  -C 10  α-olefin, said copolymer having a melting point of 115 to 130° C., a density of 0.915 to 0.940 g/cm 3  and a melt index of 0.1 to 5 g/10 min. 
     
     
       2. The pre-expanded particle of claim 1, wherein said non-crosslinked linear low density polyethylene contains at most 0.1% by weight of C 8  -C 18  fatty acid metal salt. 
     
     
       3. The pre-expanded particle of claim 1, wherein the average cell diameter is from 320 to 800 μm.